Long working days could increase risk of heart problems, study finds

We all know that spending too much time in the office can have a negative effect on your mental health, but it can also have a negative impact on your physical health, too. New research shows that working overtime could even go so far as to influence an individual's heartbeat – resulting in potentially fatal consequences.

Researchers at University College London have found that people who work for 55 hours or more a week are more likely to develop an irregular heartbeat – otherwise known as atrial fibrillation (AF) – which holds serious consequences such as stroke, heart failure and dementia.

The study

The team analysed data on the working patterns of 85,494 middle-aged men and women from the UK, Denmark, Sweden and Finland. The participants were divided into groups according to their work patterns (with 35-40 hours a week treated as the control group) and observed over the course of a 10-year follow-up.

At the end of this period, an average of 12.4 per 1,000 people had developed AF – a figure which rose to 17.6 per 1,000 in the group working 55 hours or more. Even though, interestingly, those working longer hours were less healthy in general, the findings still stood. Professor Mika Kivimaki, who led the team, said:

"Those who worked long hours had a 1.4 times higher risk of developing atrial fibrillation, even after we had adjusted for factors that could affect the risk, such as age, sex, socio-economic status, obesity, leisure time physical activity, smoking and risky alcohol use."

He added:

"Nine out of 10 of the atrial fibrillation cases occurred in people who were free of pre-existing or concurrent cardiovascular disease. This suggests the increased risk is likely to reflect the effect of long working hours rather than the effect of any pre-existing or concurrent cardiovascular disease, but further research is needed to understand the mechanisms involved."

However, there were some limitations to the study in that the researchers only asked participants about their working hours at the start on the 10-year period, so things could have changed by the time the study finished. In addition, the team were also unable to identify whether different job types held greater risk.

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What are the experts saying?

A normal heart rate should be regular and between 60-100 beats per minute when resting, but for those with AF the heart rate is irregular and can sometimes beat considerably more than 100 times per minute. Prof Kivimaki said:

"A 40% increased extra risk is an important hazard for people who already have a high overall risk of cardiovascular disease due to other risk factors such as older age, male sex, diabetes, high blood pressure, high cholesterol, overweight, smoking and physical inactivity, or living with an established cardiovascular disease."

However, he added that the, for a young person with few if any of these risk factors, the absolute increased risk of atrial fibrillation associated with long working hours is small. Professor Sir Nilesh Samani, medical director of the British Heart Foundation, also commented on the research. He said:

"Although we know some of the causes of atrial fibrillation, such as age, high blood pressure, heart valve disease and excess alcohol consumption, many patients develop the condition without an obvious cause. The suggestion that longer working hours may be a cause of atrial fibrillation is very interesting."

He added:

"Significantly, this study clearly shows that the link between atrial fibrillation and long working hours has nothing to do with the other, already known, risk factors for the condition. However, the observational nature of this research means these findings cannot confirm the cause of this relationship – it could be long working hours, it could be the type of work people do or it could be some other, unmeasured, factor."

Until further research is done, Prof Samani said the BHF would not be issuing any recommendations.

The study was published in the European Heart Journal.

Jenny L. CookJenny Cook is an award-winning writer and editor who covers health and personal finance.

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